Posts Tagged ‘taphonomy’

Because we know we can’t be found

12 October 2011

In case you missed it, today marks the end of Cephalopod Awareness Day 2011. I cannot decide if it is comedy or tragedy that the cephalopod who garnered the most awareness this week is one that probably never existed. “Triassic Kraken” has already entered the hyper-meta phase: here is a reaction to the reaction to the reaction to the early “reporting” on the story.

But amidst the orgy of credulity, incredulity, joy, anguish, laughter and rage (and whatever this is supposed to be), it struck me that something was missing. I have seen loads of skeptical remarks from vert paleo types, and certainly we are well suited to critique the work, but it seems nobody thought to ask the opinions of those that have studied the middens left behind by living octopodes.

So I did.

I fired off a list of questions to two midden experts, Dr. Richard Ambrose and Dr. Jennifer Mather, both of whom have published multiple papers on the topic of octopus middens. Both were incredibly gracious in providing detailed and thoughtful replies within hours.

My interest here was not whether McMenamin’s scenario is realistic. Clearly it is, at best, wild and highly imaginative speculation.

But I was interested whether it might be feasible to identify octopus middens in the fossil record. How we might identify vertebrate victims of cephalopod predation? And, leaving aside the whole “self-portrait” thing, is it really feasible that a giant bathypelagic squid would be exhibiting behavior associated with shallow water octopods.

In short the answers seem to be: 1) “Probably” 2) “Hard to say” and 3) “No.”

Both Dr. Ambrose and Dr. Mather were kind enough to allow me to share their comments:

Probable example of an octopus bite mark on fossil bivalve shell from Harper 2002.

me: What are the prospects of successfully identifying octopus middens in the fossil record (i.e. are they permanent enough features that they would be likely to be buried by sediment, and would they be readily distinguishable from storm deposits)?

Richard Ambrose: I think middens could be discovered in the fossil record.  Depending on the species, octopuses may den at the same location for a considerable time (“considerable” being relative, since octopuses are semelparous and most species live only a few years at most; even the giant Pacific octopus probably lives only 5 years or so) and they would continue to deposit midden items as long as they occupied the site.  Moreover, good denning sites are often limited, so even once on octopus vacated the den site another would be likely to take up residence, further building up the midden.  When we are looking for middens while diving, we focus only on the recent midden items because these are whiter and more conspicuous, but I would not be surprised to see an accumulation of midden items over many years.

Of course, many midden items are dispersed by currents.  For example, we rarely find many crab exoskeletons because they are easily swept away by currents.  Depending on the location, even heavier items like clam and snail shells can be dispersed.  So for the middens to enter the fossil record, you would need some event, like dramatic sedimentation associated with a storm or perhaps an undersea slide, to preserve the items in place.  But this is not inconceivable, especially after a storm.  I do think they likely could be distinguished from storm deposits.  Although storms might deposit a concentration of shells in one area because of local topography, most items would be widespread over the storm-affected area.

Jennifer Mather: Prospects would probably be good, some but not all fossil remains get buried in soft sediment.  Distinguished from storm deposits would be possible.  First they might have drill and chip marks on the shells–chips on clams, drills on clams, snails and sometimes crustacean claws.  Drill holes of cephs are tiny, too and specifically placed (Marion Nixon did a lot on that).  Not all shells are drilled or chipped, though.  Second, they WOULD NOT be broken.  Cephs have partial digestion externally, they scrape and digest out the soft parts leaving a disarticulated set of crab shell pieces or empty clean mollusc shells. Shell collectors prize octopus middens. So a midden would have a nice complete collection of crab parts, for instance, and if it was in soft sediment and got buried quite quickly, it might get well preserved. I remember watching the ‘fate’ of the eight blue shells of one octopuses chiton meal.  They slipped down the pile and slowly got buried, when I exhumed the whole thing much later, the blue winged shells emerged one by one, very well preserved and with a drill hole in one valve.

me: Assuming vertebrate remains would not show the drill holes characteristic of shelled prey, what signs could we look for to indicate cephalopod predation?

RA: That’s true, only shells are likely to show indisputable evidence of octopus predation.  (Octopuses also “drill” crabs, but those would be quite perishable.)  For vertebrates, they would just eat the flesh.  There might be some dis-articulation, but the fish eaten by the octopuses I’ve kept in the lab were not pulled apart, so I don’t know how common that would be.  So it would be very hard to find marks or other characteristics that would indicate consumption by a cephalopod.  There might be scrapes from the beak on bones, but I’ve never looked at/for these and I would think they would not be very distinctive.

Octopus midden from Flickr user Steven Severinghaus - Creative Commons 2.0

me: How widely distributed is midden building behavior among octopus species? Has it evolved more than once? Is it known from deep sea or pelagic species?

RA: This is really the key issue, I think.  Midden building is very common among octopuses, but it seems to me that it is most likely a simple consequence of their denning behavior and the fact that they often (but not always) bring food back to their den for consumption.  Hence, they discard prey items outside of their dens.  There is some manipulation of discarded food items and other items – like rocks – by octopuses in their dens, most often to close or partially close the opening to the den.  But I’ve never noticed anything like a systematic arrangement of items as a means of communication (like some birds do, such as bower birds) or artistic expression – no self-portraits that I’ve ever noticed, despite the intelligence of the species I’ve studied!  Note: this is not to say that something like communication through prey discard items isn’t possible.  I could see how it could evolve (and maybe that would be something to look for!), I just don’t know of any examples of it occurring.

So, as far as I know midden formation is likely to occur anytime octopuses den in one place for any period of time.  This is restricted to relatively shallow water octopuses.  Even then, most octopuses living on soft bottom habitats would not produce dens under most circumstances.  Deep sea octopuses and pelagic species do not, as far as I know, take shelter in dens or produce middens.  This makes sense; there are no caves or holes in the deep sea, for the most part.  Especially any species that would forage widely, like up in the water column, would have little reason to return to a particular place to eat.

I know of no examples of non-octopus cephalopods (squids or cuttlefish) producing middens.  Cuttlefish closely associated with reefs might be a reasonable candidate for producing middens, but I have never heard of this. Any cuttlefish or squid living in the water column would be extremely unlikely to produce middens.

JM: Middens aren’t really built.  Octopuses do build ‘walls’ of rocks in front of the home.  But when they eat prey at home, they just push out or blow out with a jet of water, or leave shell remains in the home. It’s more like a garbage heap.  We don’t know a lot about octopus species, we’re particularly short of field work.  However, midden remains have been assessed in the Mediterranean, the Caribbean and Bermuda, off the coast of Brazil and up the Pacific coast of North America (these are published papers, there are probably other assessments). My guess is that it evolved fairly early in the ancestry of octopuses, it’s likely widespread because all you need is a sheltering home and the habit of tossing your trash out.  It is limited by topography, remains aren’t found where there is a strong current, they obviously get whisked away. Middens are NOT found in pelagic species because there is no place to put them, squid do not make middens and cuttlefish probably do not either.  Deep sea octopus species might, it depends on what they find to eat.

Images

Top – Illustration from Victor Hugo’s Toilers of the Sea (1888 Crowell Edition).

Middle – Figure from Elizabeth Harper (2002) “Plio-Pleistocene Octopod Drilling Behavior in Scallops from FloridaPalaios 17:3 292-296 DOI: 10.1669/0883-1351(2002)017<0292:PPODBI>2.0.CO;2

Bottom – Photograph from Flickr user Steven Severinghaus – Used under Creative Commons 2.0.

Ours is not to look back. Ours is to continue the crack.

14 May 2010

Our traditionalist is now beginning to worry, but he will grant this one last point pour mieux sauter.  OK, the very first Cambrian fauna included a plethora of alternative possibilities, all equally sensible and none leading to us.  But, surely, once the modern fauna arose in the next phase of the Cambrian, called Atdabanian after another Russian locality, then the boundaries and channels were finally set.  The arrival of trilobites, those familiar symbols of the Cambrian, must mark the end of craziness and the inception of predictability.  Let the good times roll.

This book is quite long enough already, and you do not want a “second verse, same as the first.” I merely point out that the Burgess Shale represents the early and maximal extent of the Atdabanian radiation.  The story of the Burgess Shale is the tale of life itself, not a unique and peculiar episode of possibilities gone wild.SJ Gould Wonderful Life (1989)

Had it in my head, tindered by a typically turgid comment I left over at Jerry Coyne’s blog, to write something about the phantasmic Fezouata fauna. About contingency and determinism and prehistoriography.

The first god had, in his garden, one of these I'm sure. Ordovician marrellomorph from the cover of this week's Nature / Van Roy et al. 2010. A strong contender for my next paleo-ink.

About Wonderful Life and Crucible of Creation. About broken molds and Technicolor films. About checking the guy’s rock record and replaying life’s wobbly mistracked tape.

this is what the late eighties was like

[I biked over the library after Schluter’s talk and grabbed some books.  “That’s a small book,” the librarian remarked about the paperback version of WL, recut into hardback form, “but I’m sure it’s filled with big ideas”]

And about GOBE and rocks from space. About evolutionary anachronism and steampunk anomalocaridids and Schinderhannes. About Chengjiang and Emu Bay and Orsten.

[I Googled.]

About Caratacus and the Ordovices and predictable outcomes. About the Cincinnati arch and Creation Museum atop it. About how those that ignore history are doomed to not worry about it too much, along the way.

[I read.]

And yes about the other big and massively under-celebrated early Paleozoic news this week: Cambrian Bryozoans (!) and Gondwanan echinoderms.

[I typed.]

And ultimately about how, really, all of this maybe shows not so much about the fickle nature of history or the inevitability of intelligence or even about foolish it is to draw deep philosophical lessons from a crappy fossil record.  But that, well, the Earth was a really weird place 550, 450, 250, 50, 5 million years ago and that we have a lot more surprises in store and a lot more to learn.  But we will, in fits and starts, and what we do discover will change our picture of our place in the universe.  Or maybe it won’t.

[I hit delete.]

Because it’s Friday afternoon, and that all sounds pretty damn pretentious and sappy and inconclusive.  Why not throw together a link-heavy meta-post [I thought], then sit back and watch the links decay over the years until all that’s left is an ambiguous smear that’s difficult to make any sense of.

Then I remembered that it’s post a Fall song on your blog day.

Where Has All the Carrion Gone Again, again.

21 August 2008

Whilst yez all labor over IDs for the last post here’s some more fore yez:

all rotten and laced with clues. and bacteria.

POSTSCRIPTO: Apologies for the subliterate turn, sadly it’s not the first time.  It’s metaphorical.  It’s a coping mechanism.  My lease on blogging is neither new nor transferable.

Death Throes pt. 2: Opisthomonotony.

9 February 2008

In the incursive preamble we spiroambulated about the corpses of mummified dinosaurs, pickled pelicans, time and a piss-covered pseudo-esker of rock, rock salt and dust. So, what does all of this have to do with experimental taphonomy?

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Getting Dumb, Ghost Riding the Sticky Cretaceous Lasso etc.

17 December 2007

155802_b_lp.jpg picture by cetae

I am, of course, a Nor-Cal-ian, and so, a HUGE hyphae fan. Needless to say, this new brevium by Schmidt, Dörfelt and Perrichot, Carnivorous Fungi from Cretaceous Amber, in last week’s Science leaves me deeply stoked.

I mean, come on. Just, try asking most people to name their favorite fossil fungus (no, Ediacarans don’t count).  Well, actually we’re still out of luck since the authors don’t hazard a Christening beyond noting that the fossil fungus is unlike modern nematode-trappers. May I humbly suggest:

Keakdasneakmyces bowensis“?

So, in summary: Nematophagous fungi are A) totally terrifying (if you’re a nematode), E) totally indispensible (if you like eating vegetables), X) totally rad (in general) 4) have a fossil record going back to the Cretaceous. There are awesome diagram-laden websites, movies &c.

Yadadadig?

Postscript: Just slightly off topic, but anyone unfamiliar (or familar for that matter) with the awesome and terrifying beauty that is Cordyceps should check out this post by Neurophilospher.

postscript to the postscript – formatting issues are now solved.  sorta.  also var. typos.

Surf…and…Tuuuuurf!

3 December 2007

She’s a love mummy.

Okay, okay. So we all know that it’s a “seclusion” of embiopterans, a bazaar of guillemonts, a blessing of unicorns etc. But what do you call a group of mummies? Why, a malodor of course! Or, wait maybe that’s skunks (six cents to the first person who can come up with the collective noun for skunks without using Google).
Well, whatever it is we need it what with the announcement of yet another dinosaur mummy. Of course, the use of the term “mummy” to describe these exquisitely well-preserved dinosaurs is something of a misnomer since the mode of preservation here has nothing to do with Egyptian mortuary practices. I only wonder why they didn’t rush the press release out in late October (hint hint to anyone sitting on an unpublished volant cervid).

Given the choice, I’d be rather more excited about a “mummified” crurotarsan, or pterosaur, or amphisbaenid, or oligochaete or, well just about anything besides another hadrosaur but hey, nobody asked me. And, it’s a great excuse to re-run my “Wide-open blood-spattered Trachodon” shown above. I did that with a computer.

If you mistakenly arrived here looking for an intelligent discussion of a breaking paleontological discovery, please accept my apologies. And may I direct you to When Pigs Fly Returns or Pondering Pikaia?

That is all.

Where Has All the Carrion Gone, Again?

19 July 2007

Duh-nuh

A revisit to the beach which inspired the original, barely readable, post (Where Has All the Carrion Gone?) proved again that the Lost Coast, south of Pt. Mendocino CA is a great place to die. Or at least a great place to have your carcass wash up.

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